# Characters of different secular effects in various patches of de Sitter space

## TL;DR

This paper analyzes various secular effects in two-point correlation functions of scalar quantum fields in different patches of de Sitter space, highlighting their distinct characteristics and dependence on the space-time region and field mass.

## Contribution

It provides a detailed comparison of secular effects across different de Sitter patches and identifies their specific and generic features in quantum field theory.

## Key findings

- Secular effects vary between global, expanding, and contracting patches.
- Certain secular effects are unique to massless or tachyonic scalar fields.
- Secular effects are present in low-mass n-point functions in de Sitter space.

## Abstract

There are at least three different types of secular effects in the two-point correlation functions in scalar quantum field theories in de Sitter space-time. The first one is specific to de Sitter massless and tachyonic minimally coupled scalar fields. The remaining two are generic and are encountered practically in any non-stationary situation in quantum field theory. Furthermore there are secular effects in the n-point correlation functions for low enough mass. They are also specific to de Sitter quantum field theory. In this paper we focus on the differences between the secular effects in two-point functions. We discuss also their character in different patches of de Sitter space-time - global, expanding and contracting Poincar\'{e} patches.